In other words, the d of ad usually changes into the same letter as the first letter of the following root or word when it is a consonant: ad-fix becomes affix, and ad-sign becomes assign; therefore, making a double consonant.

Another example includes: attract as with ad-tract (drawn towards); so it has a double t. On the other hand when ad-precedes a vowel, as with adapt, it is simply ad-apt, with one d. For the same reason, there is only one d in adore and adumbrate, because ad- has combined with orare and umbra each of which starts with a vowel.

So, remember: since these Latin words begin with vowels and not consonants, the d of ad does not double as shown in the previous examples.

a capite ad calcem (Latin motto)

Translation: "From head to heel; thoroughly."

Equivalent to "from top to bottom".

Ab ovo usque ad mala (Latin phrase)

Translation: "From the egg to the apples."

A Roman phrase similar to English, "From soup to nuts"; but it means "From start to finish". This meaning is based on the fact that Roman dinners often started with eggs and ended with fruit.

From the beginning to the end of any enterprise; thoroughly, or without qualification.